Field of the Disclosure
The present disclosure relates generally to head mounted display (HMD) devices and, more particularly, to antenna systems for HMD devices.
Description of the Related Art
Typically, a head mounted display (HMD) device is connected to one or more external data sources for streaming of video or graphics content in support of an immersive augmented reality (AR) or virtual reality (VR) experience facilitated by the HMD device. Previously, the connection between an external data source and the HMD device was provided via a wired tether. However, such corded connections are relatively heavy and thus fatigue the user, or otherwise inhibit the user's mobility. As such, some HMD devices do away with the wired connection in favor of a wireless local area network (WLAN) link with the external data source via an inverted-F antenna or monopole antenna in the HMD device. Moreover, HMD devices increasingly are being configured to support wireless connections between the HMD device and various personal devices, such as a laptop computer, a smartphone, an audio system, etc., or a handheld controller via a wireless personal area network (WPAN) supported by a WPAN antenna mounted on the HMD device.
Often, sufficient isolation between an inverted-F antenna or monopole antennas utilized for WPAN and WLAN purposes in general systems can be obtained by one or more of: providing sufficient distance between the two antennas; operating the two antennas at different center frequencies; or configuring the two antennas so that they do not operate concurrently (that is, are time-multiplexed). However, these solutions typically are not practicable in HMD device implementations. The typical dimensions of an HMD device generally do not allow inverted-F/monopole antennas to be separated sufficiently to provide adequate isolation. Time-multiplexing between the two antennas in an HMD device likewise is often undesirable as doing such would significantly cut the effective bandwidths of both antennas. As for separating the antennas in the frequency spectrum, this approach would limit the number and types of devices to which the HMD device could connect. To illustrate, while IEEE 802.11-compliant WLAN antennas may operate at either the 2.4 gigahertz (GHz) band or the 5 GHz band, Bluetooth-compliant WPAN antennas operate at only the 2.4 GHz band, and thus limiting the WLAN antenna to only the 5 GHz band would prevent the WLAN antenna from connecting to access points and other WLAN-enabled devices that operate only in the 2.4 GHz band.